Phase Change

Cesar and Ming were investigating a see-through container of water. Water can be a solid, liquid, or gas. At first, Cesar and Ming said the water molecules were moving in place. Later, the water molecules were moving around each other. What change did they observe to the water?

• At first, the water was a gas. Later, it was a liquid.

• At first, the water was a liquid. Later, it was a solid.

• At first, the water was a solid. Later, it was a liquid.

• At first, the water was a liquid. Later, it was a gas.

Tags

NGSS.MS-PS1-4

Refrigerators are able to transfer energy out of a substance. At first, the substance is

a gas. The refrigerator changes the phase of the substance by transferring energy out

of it. How does this change affect the substance’s molecules? After the phase change, the molecules move....

• slower, and they move away from each other.

• slower, and they move around each other.

• faster, and they move around each other.

• faster, and they move in place.

Tags

NGSS.MS-PS1-4

Detectives find two substances at a crime scene. One is a poison, and the other is a cleaning chemical. At room temperature, both substances are liquids. To test the substances, the detectives transfer the same amount of energy into both substances, but only the cleaning chemical changes phase. How is the cleaning chemical different from the poison? The cleaning chemical has a . . .

• weaker attraction between its molecules than the poison. Its molecules now move in place.

• weaker attraction between its molecules than the poison. Its molecules now move away from each other.

• stronger attraction between its molecules than the poison. Its molecules now move away from each other.

• stronger attraction between its molecules than the poison. Its molecules now move around each other.

Tags

NGSS.MS-PS1-4

A company uses a substance that is a solid under normal conditions. This substance will be used in extreme conditions, which could make the substance’s molecules move faster and cause a phase change. How would this phase change occur, and how would the molecules of the substance be affected under these extreme conditions? Energy would be transferred . . .

• out of the substance, and its molecules would move away from each other.

• out of the substance, and its molecules would move around each other.

• into the substance, and its molecules would move around each other.

• into the substance, and its molecules would move in place.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

NGSS.MS-PS3-5

Two different cars, the Model S and Model T, use different substances in their engines. The image above shows the two substances. At room temperature, both substances are liquids. A car mechanic transferred the same amount of energy out of the two containers, but only one substance changed phase. Which car’s substance changed phase, and how did it change?

• The Model T’s substance changed phase because the attraction of the molecules was able to overcome their slower movement. Its molecules now move in place.

• The Model T’s substance changed phase because the strong attraction between the molecules made their movement slower. Its molecules now move in place.

• The Model S’s substance changed phase because the weak attraction between the molecules allowed them to move faster. Its molecules now move around each other.

• The Model S’s substance changed phase because the attraction was able to overcome the slower molecules. Its molecules now move away from each other.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

NGSS.MS-PS3-4

NGSS.MS-PS3-5

The image above shows information about two different substances in sealed containers. A scientist transfers the same amount of energy into both substances. One substance changes phase, but the other does not. Which chemical changed phase, and why did it change?

• Substance A changed phase because its molecules were able to move fast enough to overcome the attraction between them. It is now a gas.

• Substance A changed phase because the weak attraction between its molecules allowed them move faster. It is now a gas.

• Substance B changed phase because the molecules were able to move fast enough to overcome the attraction between them. It is now a gas.

• Substance B changed phase because the strong attraction between molecules made their movement slower. It is now a solid.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

An Earth scientist brought an unknown substance from underground back to her lab. The substance was in the gas phase, and was put into a sealed tank as shown above. She slowed down the molecules inside the tank and the substance changed phase. How did she do this, and how did it affect the molecules? She transferred energy . . .

• into the substance, and the molecules moved around each other.

• into the substance, and the molecules moved away from each other.

• out of the substance, and the molecules moved around each other.

• out of the substance, and the molecules moved in place.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-5

Which object has molecules that are moving?

• Only the water in the glass has molecules that are moving.

• Only the water in the ocean has molecules that are moving.

• Both have molecules that are moving.

• Neither has molecules that are moving.

How is the kinetic energy of molecules changing when the molecules move faster? The kinetic energy . . .

• is not changing.

• depends on the molecules.

• is decreasing.

• is increasing.

Tags

NGSS.MS-PS3-1

NGSS.MS-PS3-5

The fuel tank of an airplane has a device that measures the fuel’s temperature. Before the airplane took off, the temperature of the fuel was 27°C. After the airplane had been flying for one hour, the temperature of the fuel had decreased to 3°C. Which of the following must have happened to the molecules of the fuel?

• The molecules got farther apart.

• The molecules started moving slower.

• The fuel gained cold molecules.

• The molecules became smaller in size.

Tags

NGSS.MS-PS1-4